Retractable landing gear



2 Sheets-Sheet 1 Filed Oct. 15, 1943 Feb. 15, 1949. E. E; FOSTER RETRACTABLE LANDING GEAR 2 Sheets-Sheet 2 Filed Oct. 15, 1945 4 Patented Feb. 15, 1949 UNITED STATES PATENT. OFFICE 7 RETRACTABLE LANDING GEAR Edwin E. Foster, Austin, Tex.

Application October 15, 1943, Serial No. 506,405

14 Claims.

1 This invention relates to improvements in aircraft landing gears and particularly in such gears wherein a spring pulls the wheel of an aircraft into its retracted position.

It is an object of the invention to provide the wheel with means which will fold up the latter in ten seconds or less after the plane leaves the ground in order to reduce'the "drag effect. It is a further object of the invention to utilize a c'ounterweighted or spring device instead of a hydraulic system requiring an accumulator to effect a quick retracting and lowering of the wheels of aircraft.

Another object of the invention is to utilize the energy of the landing shock or the weight of the plane in settling on the ground to restore the loss of energy in the spring due to mechanical friction, air friction, etc., and this energy at landing is utilized to' provide the necessary surplus of energy that will be dissipated at each end of the tion is mounted on its gear and is supported and.

rotates upon retraction on a shaft or axle l which is preferably stationary. This shaft is mounted in a part of the aircraft such as the frame members 2, Fig. 3. Thus shaft I is the pivot axis for a large hydraulic cylinder or shock absorber 3 which is provided with two spaced arms or lugs 4.

The shaft 1 is also the pivot axis for a pair of lever arms 5 which support one end of a compression spring 6 by means of a cup 1 and a pin 8 on one end, and a roller 9 on the other end thereof. The other end of the compression spring 6 is provided with a cup l and a pivot pin H which latter is also a'stationary shaft mounted in the frame 2. A pair of arms l2 are each pivoted at one end of the shaft l l and the other ends of the arms are connected to a pin l3 to which a second pair of arms [6 are connected. Limit stops l4 and I5 are provided on the arms or prop stick l2 and l 6 which will permit the prop stick or folding arm to stop on dead center position as shown in Fig. 1. The bottom end of the arms l6 are pivotally connected to lugs I! on the cylin- A latch member [8 is pivotally connected der 3. on the shaft l and is provided with a curved thumb portion I9 which forces the arms l2 and I6 011 dead center position at pin I3 after being unlatched by means of a pull link 20. Another 2 latch 2! is pivoted on a pin 22 on the frame 2 and is operated by means of a pull link 23.

A tapered wedge 24 is slidably arranged in guide tracks 25 secured on the side of the cylinder 3 and a return tension spring 26 is secured at one end to the wedge and the otherend to a fork member 32 for the wheel. A smaller or lower cylinder 21 which carries a compression spring, not shown, for cushioning is'provided with a guide rod 28 ora customary elbow link to prevent rotation of the cylinder. Another rod 29 secured in the fork member 32 moves with the lower cylinder 21- and moves or forces the wedge 24 against the roller 9 to further load the spring 6 at the time the weight of the plane, upon landing, is taken up by the wheel 30. The dotted line position of the wedge 24 and roller 9, Fig. 1, shows the roller upon the outer fiat portion of the wedge. As the plane takes off, the wedge remains in the dotted line position due to the pressure against it and the plunger 29 will move downward away from the wedge. When, however, the plane is in the air and th pull link 20 is operated to unlatch the arms l2 and I6 and push it off of dead center at l3, the spring 6 will throw or rotate the wheel and the other parts into the position shown in Fig. 2 around the shaft I, where it is caught by the latch 2!. The pressure is now off of the roller 9 and the spring 26 will then pull the wedge 24 back to the position shown in Fig. 1 in relation to the cylinder 3.

When the latch N is released, the weight of the wheel 30 causes the parts to fall rapidly through the first part of the stroke and then be checked by the spring 6 as they come to rest in the position shown in Fig. 1 where the mechanism is latched again by the latch l8 andthus the wheel is in position for landing. The landing operation restores the loss of energy due to mechanical friction and air friction and provides the necessary surplus of energy that will be dissipated at each end of the stroke. A limit stop 3| on the frame 2 is provided to stop the travel of the arms 5 so that, in the position shown in Fig. 2, it will be assured that the wedge 24 will have the roller 9 completed "off of its surface so that the spring 26 will retract the wedge 24. While it is not specifically shown, the customary electrical indicators may be provided to indicate whenthe wedge has been retracted, or mechanical 'means provided to prevent the unlatching of latch 2| unless the wedge is in the retracted position. In the latter case a third button or lever can be provided to'positively retract the wedge in case it were to stick due to failure of spring 26. The operation of the landing gear is summarized as follows:

Assuming that the elements are in the position shown in 1 inv which the wheel. has been receive the. weight oi the aircrait As the -.wheel; begins to-contact the,.ground, the-Weightoi the,

plane gradually settles on the cylinders 3 and 21 which by telescoping action transmit the Weight of the plane plus the shoclgoj landing to the hydraulic fluid and/or springs in the cylinders. This results in a relative rnovep ent of the cylinders 3 and 21, that is, cylinder 21 moves up into cylinder 3 and-asthis actiontalsesplace rod 29 moves or forces the wedge gfinp; wardly relative to cylinder 3. This will force .ifi gi Q, PY? Z i? 9 .1%- 9. EQY h arms aterlockw s FSPPFl' Shag? thereby further loading or compressing the spring 6. This further loading replaces the energy which s lostdueto mechanicalandair friction will be dissipated at each end of the a te.

Upon take-oi of theplane the pul l link 29 is operated to; move latch" member ill upwardly ea i e r i e f e the r i' ib m rm? tiqn i9 will iorc the;arms lg'and; lfi ofi ceiiter at pin i3; that is, movethe se armsoutward-lyt 'Phus the-spring E- pushingegainst-the shaft i will force the aixnslZ and IE totold up as-in Fig. 2 which :will throw the wheel 38 upwardly until the latch 2|engages-the fork-meriiber 32' to tim hold th wheel. in the-horizontal or folded up position. In the latter positionthe iorceof the-spring 6;being now released from the roller S -and the Wedge 24=sothat the latter will be. pulled; back by 'the. spn'ngefit Theiparts are thus in a position to i'epeat-the-operation of lowering the wheehin position for-landingthe plane.

Fromthe-foregoing. it. will be; apparent.- that thespring dais-loaded by the .fall 1 of the .wheel and its parts solthat when thewheel is -to. be; retracted, the. loaded :springwill throw thawheel. back to its' folded-supposition" I':claim,as my invention:

1. A retractable landing gear for an aircraft wheel: 5. comprising. a.-. shaft: secured one a part oi:

the aircraft, a wheel supporting memberlm onnted to rotateton the shaft; a pair. ofrlever-arms rotatablp mounted. on said :shaft intermediate.- their ends an drabutting rat :one..-end -on;.the; supporting membera. .pair of. -armsPiS otally connected to each other, and one; end;- pivotally, connected to thasupporztingmember; and the other end to a fixed: support, a. compression spring; connected atl one; end to. the other ends oi {the lever; arms and theother rend-to the pair of arms, and-means ori ate in .t es e ondw a rf ms depos tion to. main nth w eat ue rt n zmeeibernfihe -downi positionof the wheels.

as" c a t-ac ese z ua o a e? a heslia e191? ed; to

tas s time "pr s ekin i' a w eased? th se-P s nae. 24 a leend the other rid-to, e other an the of means for latchingi the second mentioned pair of arms in position to maintain-thewheel supportinggnemberin the.-.down position of the wheel; and-a second latch forisecuring thetwheel' 75 connection oi the two pairs of arms, and in which the first-mentioned latching means is provided with a. curved: thumb portion to contact the piyotal.con11ection of the arms to retract the wheel upon movement of said latching means.

5 Aretractable landing gear for an aircraft wheel comprising a shaft secured on; apart of the aircraft, a'wheel supporting membermounted to rotate ontheshait; a pairof lever armsrotatably mounted on said shaft intermediate its ends and abutting-atcneend on the supporting member, apair-oi. arms pivotally "connected to each other-and one end pivotally connected: to the supporting member andthe ctheri end to afiged support-,- a compression spring connected at'one end" tothe. otherends: of the-ilev'ert arms. and: the other. end: to.- thepairof arms means for latchingthe. second-"mentioned; pair of? arms in position to maintain the wheel supportingmeme. her in the-down position of the. wheel; asecond latch for. securing thewheel and. its :sH-PDQlE-ting: member inithe. retracted; position: andza Wedge; member slidably mounted 3 in the w hee1 support ins: member and. zc operat nawi h-thelevenarms t be bi i s-fi ds o.- te sion.- l e:.sprineiw e and; the other to Ethe aircraft andgboth CQQPQP tme; o. bsor amina; h cks ,a spri g 9 7.- nected to one of the membersrtoforce the wheeg' ait-e etracted. osi on. moose.- o cte to both members operailv when: the, wheel touches the reund e el anoremeatpith rmhers ak s la a e t erebr e sreihei aere a i i e er w ich; wasz x eedes s i e e me han-ita and eir rici oa,

tr ct blee an egr ear; a es: ircra t Wheel. c m r na air tr lescopine and el: a ire y. m a e; 19Q :%12 m. memb i e iiet es aethe h el onne ted herei e ad he t fir; wn ct l ihe ai c a a he-it conneeted'to the aircraft andpn which the; other member; ii talirm antedra air i l v rotatably mounted on- ,the:shaft;appr atelyarena n s hat-coil earl:- l avms ne .a 1 .9 1 .11a utt n qn etfir bpo e .o he me. t rse-com r s e e ies eas etw n m; a1 "nib ble wit -the he heel-z t. mounted; pair oidever-arms ythaab tt gcends 1.Are reptablsie diae. eer d n 1 7, n T .Qh. a E ?'l E i rmsand. et. rep er dsi r aett 5. to. hafia d p ort andthe other membento lock the wl reel icy its members in the down position.

A retractablelanding-gearforan aircraft wheel comprising a: pair ot telescoping andrelatively movable shockabsorbing members of which one has the wheel connected thereto and the other is connected to the aircraft, a shaft connected to the aircraft and on which the other member-is pivotally mounted, a pair of lever arms rotatably mounted on the shaft approximately intermediate the ends thereof and having one end of each in abutting contact with one of the members, a compression spring mounted between the other ends of the arms and a fixed support, and means secured to and movable with the member on which the wheel is mounted to rotate the pair of lever arms by the abutting ends thereof when the wheel contacts the ground and relative movement of the members takes place to thereby restore the energy in the spring which was expended due to mechanical and air friction, said means including a tapered wedge movable with the member on which the wheel is mounted.

10, A retractable landing gear for an aircraft wheel-comprising a pair of telescoping and relatively movable shock absorbing members of which one has the wheel connected thereto and the other is connected to the aircraft, a shaft connected to the aircraft and on which the other member is pivotally mounted, a pair of lever arms rotatably mounted on the shaft approximately intermediate the ends thereof and having one end of each in abutting contact with the other member, a plurality of arms connected at one end to the other member and the other end to a fixed support, a compression spring mounted between the other ends of the arms and the fixed support, means secured to and movable with the member on which the wheel is mounted to rotate the pair of lever arms by the abutting ends thereof when the wheel contacts the ground and relative movement of the members takes place to thereby restore the energy in the spring which was expended due to mechanical and air friction, and a latch member connected at one end to rotate on the shaft and the other end cooperating with the second-mentioned arms to lock the members with the wheel in the "down 7 position of the latter.

.to a fixed support, a compression spring mounted between the other ends of the arms and the fixed support, means secured to and movable with the member on which the wheel is mounted to rotate the pair of lever arms by the abutting ends thereof when the wheel contacts the ground and relative movement of the members takes place to thereby restore the energy in the spring which was expended due to mechanical and air friction, saidsecond-mentioned arms each comprising a pair of arms pivotally connected to each other, and a latch member connected at one end to rotate on the shaft and the other end cooperating with the second-mentioned arms at the pivotal connection of both arms to lock the members with the wheel in the down position of the latter.

12. A retractable landing gear for an aircraft;

support, a compression spring mounted between the other ends of the arms and the fixed support, means secured to and movable with the member on which the wheel is mounted to rotate the pair of lever arms by the abutting ends thereof when the wheel contacts the ground and relative movement of the members takes place to thereby restore the energy in the spring which was expended due to mechanical and air friction, said second-mentioned arms each comprising a pair of arms pivotally connected to each other, and a latch member connected at one end to rotate on the shaft and the other end cooperating with the second-mentioned arms at the pivotal connection of both arms to lock the members with the wheel in the down position of the latter, said latch member having a curved thumb portion to contact the pivotal connection when the arms are rotated relative to each other.

13. A retractable landing gear for an aircraft wheel comprising a pair of relatively movable telescoping members one of which is provided with the wheel and the other is pivotally secured to the aircraft, said members absorbing landing shocks, 2, spring hearing at one end on the aircraft and the other end to the pivotally mounted member to retract the wheel, and means on the 7 said members absorbing landing shocks, a spring connected at one end to the aircraft and the other end to the pivotally mounted member to retract the wheel, and means operative when the wheel touches the ground and relative movement of the members takes place to restore the energy in the spring which was expended due to mechanical and air friction.

EDWIN E. FOSTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Giovannoli Nov. 29, 1938 Larague Dec. 10, 1940 Brie Oct. 28, 1941 FOREIGN PATENTS Country Date France Oct. 3, 1938 France e- Sept. 25, 1939 Number Number 

